148 FOOT AND STROBELL. 



EXPLANATION OF PLATE B. 



Photo. 7. A small piece of the cytoplasm of an oocyte, second order. Un- 

 stained. The egg was killed in i % osmic, and after one hour crushed on the 

 slide. This was to demonstrate the presence of the osmophile granules to com- 

 pare with those of No. 9. X 900. Medium, distilled water. 



Photo. 8. Ditto. Changing focus in order to reproduce the three tiny gran- 

 ules, two on the left and one on the right of the preparation. In No. 7 the 

 two on the left (out of focus) appear as tiny faint rings. 



Photo. 9. Section (3 //) through the cytoplasm of an ovarian egg at free end 

 of ovary. Granular aggregations of archoplasm and osmophile granules, such as 

 are found in the oogonia or tiniest oocytes, and in eggs of later stages, both in 

 the ovary and cocoon. C/. Nos. 4, 5, 7, 8, 10, 12, 13. Fixative, chromo-acetic 

 followed by osmic. Hardened in alcohol, 24 hours. Iron haematoxylin. X S60. 

 Medium, xylol balsam. 



Photo. 10. Nucleus in a macromere of a segmenting egg, showing two nucleoli 

 and chromatic thread. Fixed under Zeiss 2 mm. immer., i % osmic acid. Dela- 

 field haematoxylin. Exposure i^ minutes, as the light was transmitted through 

 the entire egg. X 900. Medium, distilled water. 



Photo, ii. Section (3 fi) of telophase of first maturation spindle. Cf. Text- 

 fig. II. Fixative, chromo-acetic. Hardened in 5% formaldehyde, 48 hours. 

 Iron haematoxylin. X 860. Medium, xylol balsam. 



Photo. 12. Section (3 fi) of oocyte, second order. Killed in chromo-acetic, 

 washed in water, followed by i % osmic acid for 30 minutes, to differentiate the 

 osmophile granules. Hardened in alcohol. Unstained. X 500. Medium, glycer- 

 ine. Cf. Text-fig. I. Attraction sphere and the refractive sperm indicated, 

 although the egg is unstained. 



